BSG and hepatocellular carcinoma: Currently, it is recommended to classify EVs by (1) physical characteristics, such as size or density with specific ranges defined, e.g., <200 nm (small EVs), or >200 nm (medium/large EVs); (2) biochemical and molecular components, e.g., epithelial cell adhesion molecule (EpCAM)+/CD147+ EVs; and (3) descriptions of conditions or cell of origin, e.g., HCC-derived EVs [6].